Cold war was increased due to U2.

1)       While preparing for Paris Summit, the spy airplane of America was attacked by Russia in its area.
2)       Russia got upset due to the spy activity of America.
3)       Russia charged America that it was a sort of disturbance in peace.
4)       America justified it by telling that they wanted to know the Russian secret preparation for arm forces.
5)       The Paris Summit got over on 19th May 1960.
6)       In this Summit, Russia condemned America by raising the issue of U2 Airplane.
Hence, due to the failure of Summit the cold war became more severe.